1. Field of the Invention
The present invention generally relates to an ignition unit for igniting the burner of a burning appliance (e.g., a water heater, a heating apparatus et cetera) which makes utilization of the combustion of liquid fuel (e.g., kerosene) or gas fuel (e.g., gas). This invention relates more particularly to an ignition unit which is configured such that fuel, blown out from the burner, is ignited by a spark discharge from an ignition electrode and is burned.
2. Description of the Related Art
Such a type of ignition unit is called the “ignitor”. One such example of the ignition unit of this type has been known in the art, which is comprised of an ignition electrode capable of generation of spark discharges and a transformer mounted in the inside of a casing. The transformer receives a supply of electric power from a commercial power source and then voltage-transforms it into a high voltage for discharge at the ignition electrode, and the transformer and the ignition electrode are connected together so that an electric current of such a high voltage flows to the ignition electrode (see Japanese Utility Model Kokoku Pub. No. 1989-8859).
In addition, there is proposed another example of the above-described ignition unit which is characterized in that the connection between a high voltage output part on the casing side and an ignition electrode is established when the former is inserted into the latter (see Japanese Patent Kokai Pub. No. 2001-248838). In this prior art technique, the casing-side high voltage output part is formed by a pair of elastic plates which are in elastic contact with each other. And, a plate-like connection part of the ignition electrode on the base end side thereof is inserted between these elastic plates and, as a result of such insertion, the connection part is held firmly between the pair of elastic plates.